unless you turn the gains way down, it's gonna sound like "BUMP! BUMP! BA DA BUMP! *insert the sound of voice coils locking up here*" Seriously man.....those subs don't need anywhere near that power, especially in a ported enclosure. Remember, the whole point of a slotted enclosure is to make the woofer more efficient (ie. less power = more sound).
pickups are a whole different world than cars. i had my exact same sub that i have in my pickup right now in a oldsmobile delta 88 in the trunk pointed toward the tail lights. same box volume, same amp. 130 decibils. that same sub/amp combo is pushing 137 right now in a ford ranger. so to awnser your question, yes you probably will lose some SPL due to the increase in cabin space, but it will still sound good.
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